A week after two dockless bike-share companies abandoned operations in the nation’s capital, citing restrictions on the number of bikes they could operate in the city, advocacy groups are calling on officials to think bigger about bike-share — like 20,000 bikes big.

A city the size of D.C., with its existing bike infrastructure, demands 20,000 shared bikes, the groups said in a petition addressed to Mayor Muriel E. Bowser (D) and District Department of Transportation Director Jeff Marootian.

“Dear DDOT: Plan for 20,000 shared bikes, with enough racks and protected lanes for everyone,” the petition says, calling for a sizable expansion as the city transportation agency considers permanent regulations for the bike operators.

The District’s ongoing testing of dockless bike systems allows private companies to deploy a maximum of 400 bikes or scooters or a combination of the two. Operators have complained the number is too small to make their business viable and have asked the city to expand the cap. The dockless pilot program began in September and is set to end next month.

Allowing thousands more bikes in the city’s public spaces would help it reach its goal of having 25 percent of all commutes be via walking or biking by 2032, advocates say.

“Getting there will require bold action,” reads the petition signed by the Washington Area Bicyclist Association, the Coalition for Smarter Growth, Greater Greater Washington and DC Sustainable Transportation. “One significant opportunity to reach this goal is through growing our shared bicycle and scooter fleets to 20,000, while setting reasonable rules to keep public space open for everyone.”

Such a sizable expansion, the groups say, would “help the dockless systems flourish and grow into an integral part of this future.”

City transportation officials will soon be making a decision on how the systems will be regulated after the pilot ends next month. However, they have not decided whether they will lift the 400-vehicle cap.

“There is no one right answer to that question about the right number of bikes or scooters that might be out there,” Sam Zimbabwe, a top DDOT official, said Monday on the Kojo Nnamdi Show.

“We want to see alternative modes of transportation — biking, non-auto modes —be more available and more accessible to people across the District,” he said, noting that through the pilot program the city has tried to allow a new type of activity to come into the city and evaluate how often vehicles are being used, who is using them, what they might be replacing in terms of trips.

The advocacy groups concluded 20,000 bikes would be a good balance for D.C based on a recommendation from the Institute for Development and Transportation Policy for cities to have 10 to 30 bikes per 1,000 residents. Other industry leaders have suggested 10,000 to 20,000 would be a good base.

Toby Sun, chief executive of LimeBike, which operates bikes and scooters in the District, said in October that the city would need 20,000 bikes.

“It is a big city. A lot of usage,” said Sun in an interview with the Post. “If we truly want to have a bike-share system that people very conveniently use, and more instead of driving, we need to have the coverage.”

Chinese startups Ofo and Mobike last week said they were abandoning DC in part because of the restriction on 400 bikes on the ground, which they said did not provide the needed density per bike to have a sustainable business in the city. Five other companies remain in the pilot program, but three are primarily providing scooters. Their departure troubled advocates who say this leaves DC commuters with fewer options.

“What DC really needs is not fewer shared bikes, but more — around 20,000,” David Whitehead, a housing program organizer at Greater Greater Washington wrote Monday in a column making the case for more dockless bikes.

“While there are reasonable concerns about how dockless vehicles fit into road and sidewalk space (such as not blocking walkways with parked bikes),” Whitehead said. “dockless bikes and scooters offer space-efficient, green, healthy transportation options that are accessible to many residents.”